<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
    <h1>我是标题:<span class="s"></span></h1>
    <input type="text" id="i1">
    <input type="text" id="i2">
    <button onclick="f1()">按钮</button>
    <script>
        function f1(){
            let inputE1 = document.querySelector('#i1');
            console.log(inputE1);
            var x = inputE1.value;
            console.log(x,typeof x);
            console.log(parseFloat(x));
        }
        let spanE = document.querySelector('.s');
        console.log(spanE);
        spanE.innerHTML = '我是span';
        let inputE2 = document.getElementById('i2');
        console.log(inputE2);

    </script>
</body>
</html>